【tensorflow】tensorflow:Scale of 0 disables regularizer原因

tensorflow:Scale of 0 disables regularizer原因

- 在运行tensorflow时候，遇到日志输出：

INFO:tensorflow:Scale of 0 disables regularizer.

开始以为是哪里出错了，仔细检查了代码后发现，原因是：使用tf.contrib.layers.l2_regularizer时候将scale参数，也就是l2正则强度设为了0.0，看以下源码：

def l2_regularizer(scale, scope=None):
  """Returns a function that can be used to apply L2 regularization to weights.

  Small values of L2 can help prevent overfitting the training data.

  Args:
    scale: A scalar multiplier `Tensor`. 0.0 disables the regularizer.
    scope: An optional scope name.

  Returns:
    A function with signature `l2(weights)` that applies L2 regularization.

  Raises:
    ValueError: If scale is negative or if scale is not a float.
  """
  if isinstance(scale, numbers.Integral):
    raise ValueError('scale cannot be an integer: %s' % (scale,))
  if isinstance(scale, numbers.Real):
    if scale < 0.:
      raise ValueError('Setting a scale less than 0 on a regularizer: %g.' %
                       scale)
    if scale == 0.:
      logging.info('Scale of 0 disables regularizer.')
      return lambda _: None

  def l2(weights):
    """Applies l2 regularization to weights."""
    with ops.name_scope(scope, 'l2_regularizer', [weights]) as name:
      my_scale = ops.convert_to_tensor(scale,
                                       dtype=weights.dtype.base_dtype,
                                       name='scale')
      return standard_ops.multiply(my_scale, nn.l2_loss(weights), name=name)

  return l2

可见最终原因就是这个。

- 解决方案：

from tensorflow.contrib.layers import l2_regularizer
l2_reg = l2_regularizer(0.001)

也就是将正则系数设为大于0的数，或者不需要正则化的时候取消正则操作。